As a monitor mounted in a cab of a hydraulic excavator and the like, a monitor including a liquid crystal display has been typically known (see, FIG. 5 of Patent Literature 1).
In such a monitor, circuit substrates such as a power supply substrate and a control substrate are disposed on a back of the liquid crystal display. The circuit substrates are electrically connected to each other by a flexible flat cable. During operation of a working vehicle such as a hydraulic excavator, vibration occurring by driving an engine and a hydraulic device installed in the working vehicle or vibration occurring during digging and the like by working equipment attached to the working vehicle is transmitted to the monitor. When a forklift is used as the working vehicle, vibration occurs during cargo handling (i.e., loading/unloading cargo) and during travelling. There are a variety of amplitudes, directions and occurrence frequency of the vibration occurring during digging, cargo handling or travelling. When the vibration is transmitted to the above-described flat cable installed in the monitor, there is a possibility of such a failure as the flat cable may be rubbed against other portions to break a coating. Accordingly, it is necessary to avoid a design of an unnecessarily long flat cable. For this reason, a flat cable as short as possible is used for connecting adjacent terminals (connectors) on the respective circuit substrates.
There has been proposed a wiring structure for preventing vibration and the like of a flat cable whose one end is soldered to a substrate, whereby tension does not act on a soldered part and bending stress is not generated (see, for instance, Patent Literature 2).
In this wiring structure, depending on a width of the flat cable, one slit or two slits are formed near the soldered part of the substrate. The flat cable is put through (one of) the slit(s) and is drawn out of a back surface of the substrate (the soldered part of the substrate defines a front surface). Then, the flat cable is returned to the front surface by passing around an end of the substrate or by passing through the other of the slits. With this wiring structure, since the flat cable is restrained in both width and longitudinal directions by being put through the slit, the vibration of the flat cable is suppressed to avoid acting of pulling force on the soldered part and generation of bending stress, so that solder peeling can be prevented.